The Bezold effect is an optical illusion

Optical illusion

An optical illusion is characterized by visually perceived images that differ from objective reality. The information gathered by the eye is processed in the brain to give a perception that does not tally with a physical measurement of the stimulus source...

, named after a German professor of meteorology, Wilhelm von Bezold

Wilhelm von Bezold

Johann Friedrich Wilhelm von Bezold was a German physicist and meteorologist born in Munich, Kingdom of Bavaria....

 (1837-1907), who discovered that a color may appear different depending on its relation to adjacent colors.

It happens when small areas of color are interspersed. An assimilation effect called the von Bezold spreading effect, similar to spatial color mixing, is achieved.

The opposite effect is observed when large areas of color are placed adjacent to each other, resulting in color contrast.